Description
Light intensity and nitrogen (N) availability are important factors influencing the growth of C4 forage species. Trade-offs may occur in the adaptive responses of species to shading and N inputs, and functional shoot traits can help to explain the consequences of these responses for species performance. Our objective was to gain understanding of the mechanisms between traits of five C4 perennial grasses determining above-ground dry matter yield (DMY) when both resources, light and N, vary. Forage grasses were grown in six shading conditions (full sunlight vs. five positions between Eucalyptus dunnii rows) with two N levels (0 vs. 300 kg N ha-1year-1) and clipped when the canopy reached 95% light interception. Path analysis was used to explore the relationship between DMY, shading levels, N nutrition index and shoot traits. Dry matter yield increased between 126 to 569 g dry matter m-2 with N fertilization. Nitrogen nutrition index was the most important predictor for determining DMY followed by shading level. Increased shading reduced DMY by 9.5 g DM m- ² for each 1% of increase in shading. DMY was also modulated by shoot traits such as specific leaf area and leaf area index, but with different responses according to species, highlighting different strategies to cope with changes in light and N availability.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Differential Responses of Yield and Shoot Traits of Five Tropical Grasses to N and Distance to Trees in Silvopastoral Systems
Light intensity and nitrogen (N) availability are important factors influencing the growth of C4 forage species. Trade-offs may occur in the adaptive responses of species to shading and N inputs, and functional shoot traits can help to explain the consequences of these responses for species performance. Our objective was to gain understanding of the mechanisms between traits of five C4 perennial grasses determining above-ground dry matter yield (DMY) when both resources, light and N, vary. Forage grasses were grown in six shading conditions (full sunlight vs. five positions between Eucalyptus dunnii rows) with two N levels (0 vs. 300 kg N ha-1year-1) and clipped when the canopy reached 95% light interception. Path analysis was used to explore the relationship between DMY, shading levels, N nutrition index and shoot traits. Dry matter yield increased between 126 to 569 g dry matter m-2 with N fertilization. Nitrogen nutrition index was the most important predictor for determining DMY followed by shading level. Increased shading reduced DMY by 9.5 g DM m- ² for each 1% of increase in shading. DMY was also modulated by shoot traits such as specific leaf area and leaf area index, but with different responses according to species, highlighting different strategies to cope with changes in light and N availability.
